Out of all the animals described on this site, only one has real pest status. The symphylans, or garden centipedes are reviled by farmers and gardeners across the world for eating the roots of our crops, as well as causing specific and unforgiven damage to Mrs Gertrude Popplewell's lettuce seedlings last year. Though she could certainly find comfort in the fact that symphylans prefer rich, fertile soils, with a decent soil structure. Well done Mrs Popplewell.
Undoubtedly, symphylans can cause a lot of damage. However, when gardening and farming are not issues, they are an important detritivore in forests, breaking down organic matter and freeing up nutrients into the soil. Some species are omnivorous, some herbivorous. One species at least is predatory. And they do look a little like centipedes, if you don't look too closely.
Morphology had placed Symphyla in a group closer to pauropods and Diplopoda, the millipedes. However, in a rash act of flip-flopping, recent DNA studies mean that once again, maybe Symphyla might be happier linked more closely with Chilipoda, the centipedes. Which party to go to? Do the meat platters of the centipedes trump the vegetarian hummus dips and carrot sticks of the millipedes? We just don't know.
And then, all four members of the Myriapoda are really only distantly related to each other anyway. And round it all goes. Sounds familiar? Taxonomists and cladisticians working out the complex relationships of the Entognatha have a hard enough time, but in Myriapoda, there are, at the moment, three differing ways to classify their relationship, all with good reasons why someone else's view might be more correct in the end.
Being sightless, as are most of the other soil animals, they rely on their antennae to work out their world. Luckily, as with many of the other soil animals, they are able to regenerate their antennae and limbs, through moulting, which occurs throughout their one year of life.
There are only two families of symphylans- the Scutigerellidae and Scolopendrellidae. Beautiful names, but sounding more like two warring alien nations than soil animals. They can be told apart by the more snake headed shape of the Scolopendrellidae compared to the rounded head of the other. Scolopendrellidae also have twin lines of upturned spikes called paradonta running dorsally backwards from the head along each tergite.
Symphylans have been found 1 metre down some soils. Although they can't generally create their own holes through the soil, they can push between soil particles as well as down holes left by larger invertebrates and rotted roots. To gain better purchase in the soil, at the base of each leg is a stiff spine, as well as a small sac, used in osmotic pressure regulation and fluid exchange.
Juveniles start with six pairs of legs, and finish after six moults as an adult with twelve pairs.
The largest symphylan in the world is Hanseniella magna, an endemic Tasmanian cave dweller. It is one of only a few true symphylan troglodytes. It measures around 30mm.
All symphylans lack pigment and have a slightly translucent quality, making them stand out from the Diplopoda and Chilipoda. But as is noticable in the photos below, they can absorb a certain amount of pigment from food, giving them a reddened or yellowed appearance. This would be similar to our skin turning orange from eating too many carrots or being a narcissistic US president.